> All these schemes while claiming to be immutable are really not, firstly the last block is always subject to being overridden by a longer chain with more bloc

> All these schemes while claiming to be immutable are really not, firstly the last block is always subject to being overridden by a longer chain with more blocks, thus everyone waits for multiple blocks(confirmations) before accepting a transaction as committed Not in chains with synchronous consensus and instant finality. No forking.